1. Field of the Invention
The present invention relates to a dispensing device for dispensing compressed fluid from a can and a dispensing system comprising the dispensing device and can.
2. Description of Related Art
Dispensing fluid, particularly expandable fluid, from a compressed can is useful for many do-it-yourself products. One product in particular is spray foam for sealing and thermal insulation applications. Spray foam is available as a foamable liquid under pressure in a can. It is common to dispense the foamable liquid through an application tube (or straw) attached to a valve on the can. Upon release from the can the foamable liquid expands into foam and fills gaps and/or provides a thermal insulating seal. Foamable liquids include foamable latex and foamable polyurethane formulations.
One challenge with spray foams is that residual foamable formulation in the application tube of the dispenser is free to continue to expand after applying the spray foam formulation to a location. As a result, residual foamable liquid continues to expel from the application tube even after application of the foamable liquid is complete. The expanding residual foamable liquid can drip from the application tube to create unintended messes. Alternatively, the user must continually wipe clean the dispensing end of the application tube as residual foamable liquid expands within the tube. To avoid drips and the need to continually wipe the end of an application tube, it would be desirable to have a dispensing device for use with compressed expandable liquids that would obviate continuous expansion of residual foamable liquid out from an application tube after desired application of the foamable liquid is complete.
U.S. Pat. No. 5,549,226 ('226) discloses a device for operating propellant cans that can be useful for addressing the aforementioned problem. The device in '226 comprises a bendable application tube that can bend back on itself and the open end of the straw placed over a nipple to seal it. Inserting a nipple into the end of an application tube will itself displace fluid out from the application tube around the nipple resulting in foam being undesirably disposed around the nipple area and possibly the fingers of a user inserting the tube over the nipple. In contrast to the device of '226, it is desirable to avoid having to insert anything into the end of the dispensing tube in order to seal the end. That is, it is desirable to be able to seal the dispensing end of the dispensing tube from inside the tube.
The Dow Chemical Company offers a foam dispensing gun for GREAT STUFF PRO™ brand spray foam. The spray gun is available in three different grades: PRO 13, PRO 14 and PRO 15. Each of the guns has a port onto which a can of GREAT STUFF PRO™ brand spray foam attaches thereby releasing the compressed foam formulation into a barrel of the gun. Extending through the barrel is a rod that is spring loaded to seal from inside the barrel an outlet or dispensing end of the barrel. A trigger is attached to the spring loaded rod so that upon pulling the trigger the rod is retracted from the dispensing end of the barrel and foam formulation is free to flow from the can through the barrel around the retracted rod and out from the dispensing end. Upon release of the trigger the spring repositions the rod back into sealing position in the dispensing end of the barrel. This dispensing gun design requires a spring-loaded rod to achieve internal sealing of the dispensing device. Including a spring increases cost and complexity during manufacturing. It is desirable to have a dispensing device capable of sealing from the inside but without requiring a spring-loaded rod.